Conventional polymeric ionic liquids are disclosed in, for example, (1) Anne-Laure Pont et al., “Pyrrolidinium-based polymeric ionic liquids as mechanically and electrochemically stable polymer electrolytes,” Journal of Power Sources 188 (2009) 558-563, (2) Markus Döbbelin et al., “Synthesis of pyrrolidinium-based poly(ionic liquid) electrolytes with poly(ethylene glycol) side chains,” Chemistry of Materials (2012) 24, 1583-1590, and (3) Jae-Kwang Kim et al., “Improving the stability of an organic battery with an ionic liquid-based polymer electrolyte,” RSC Advances, 2012, 2, 9795-9797.